醫(yī)學(xué)微生物學(xué)課件：8-10腸道致病菌

1、TuberculosisDiarrheal dsHepatitis BHIV/AIDSMeaslesAcute RespInfectionNeonatal tetanusWhooping coughWorm infectionsMalariaThe Top Ten Infectious Disease KillersWorld Health OrganizationEnteric Gram-negative rods (Enterobacteriaceae) (腸桿菌科) Escherichia (埃希菌屬)Salmonella (沙門菌屬)Shigella (志賀菌屬)Vibrio (弧菌屬

2、) V. cholerae (霍亂弧菌)V. parahemolyticus (副溶血性弧菌)Helicobacter (螺桿菌屬) and Campylobacter (彎曲菌屬) Helicobacter pylori, HP(幽門螺桿菌)Campylobacter jejuni (空腸彎曲菌)G rods, in irregularpili, most have flagellum (besides Shigella)Ag-O, H, K (Vi)Biochemical reaction: identificationMost are normal flora in intestine

3、tract, few are pathogensvariation: drug resistance， H-O, S-RE. coli大腸埃希菌Salmonella傷寒沙門菌Shigella 痢疾志賀菌E. coli with fimbriae O (lipopolysaccharide )Ag somatic Ag(菌體Ag) H (flagellar) Ag鞭毛Ag K Ag Vi AgCapsular AgMicrocapsule(K Ag) of E.coliE.coli - +Shigella + - - -S.typhi + - -/+ +Other Salmonella - +

4、+ Sec.1 Escherichia 埃希菌屬Escherichia Coli (E.coli)大腸埃希菌Flagella (H Antigen)Capsule (K Antigen)LPS (O Antigen)Structure of the E. coli Cell Outer membraneInner membraneThe Numbers of E. Coli flora (大腸菌群數(shù))：3個/L drinking water 5個/100ml, soda pop, juiceTotal number of bacteria: 100個/ml drinking water一.No

5、rmal flora in intestineInfection out of intestine tract (normal flora, endogenic infection, 內(nèi)源性感染)Urinary tract infection, pyogenic infection, septicemiahemolysin/K Ag/P piliMolecular biology and genetic engineering 一. Normal flora in intestine tractDiarrhea (pathogenic, exogenous infection)ETEC-LT,

6、ST-infant/travelers diarrheaEIEC-piliresembles shigellosis, bloody and pus feces (痢疾樣膿血便)EPECadherence watery diarrhea in infantsEHEC(O157:H7)-pili,SLThemorrhagic colitis, hemolytic-uremic syndrome, HUS(溶血性尿毒綜合征)EAggECtoxin,piliinfant acute and chronic diarrhea in infants (嬰兒持續(xù)性腹瀉) 二. Pathogenic E.c

7、oli travellers diarrhea/infants diarrhea milder diarrhea like cholera (霍亂樣腹瀉) pathogenic materials：colonization factor(定植因子)EnterotoxinETEC (Enterotoxigenic E. coli )腸產(chǎn)毒型大腸埃希菌Heat labile enterotoxin, LTA: enter into cellcAMPhypersecretionB: attaches to the GM1 gangliosideHeat stable enterotoxin, STc

8、GMPhypersecretionis a common cause of “travelers diarrhea” and a very important cause of diarrhea in infants in developing countries. ETEC adheres to epithelial cells of the small bowel. Some strains of ETEC produce a heat-labile enterotoxin (LT) that is under the genetic control of a plasmid. Its s

9、ubunit B attaches to the GM1 ganglioside at the brush border of epithelial cells of the small intestine and facilitates the entry of subunit A into the cell, where the latter activates adenyl cyclase, which results in intense and prolonged hypersecretion of water and chlorides and inhibits the reabs

10、orption of sodium. The gut lumen is distended with fluid, and hypermotility and diarrhea ensure, lasting for several days. LT is antigenic and cross-reacts with the enterotoxin of Vibrio cholerae（霍亂弧菌）.ETEC (Enterotoxigenic E. coli )腸產(chǎn)毒型大腸埃希菌bloody, copious diarrhea, resembles shigellosis （Children/

11、adults）Pathogenic factors：protein on outer membrane refered to invasiveness(與侵襲有關(guān)的外膜蛋白)Invading intestinal mucosal epithelial cellsEIEC (Enteroinvasive E. coli )腸侵襲型大腸埃希菌produces a disease very similar to shigellosis（志賀氏細(xì)菌性痢疾）. The disease occurs most commonly in children in developing countries and

12、 in travelers to these countries. EIEC produces diseases by invading intestinal mucosal epithelial cells.EIEC (Enteroinvasive E. coli )腸侵襲型大腸埃希菌Is an important cause of diarrhea in infants（watery diarrhea，no bloody feces ）adhere，reproduce on the surface of small intestine mucus membrane (在小腸粘膜表面大量繁殖

13、)，loss of microviliEPEC (Enteropathogenic E. coli )腸致病型大腸埃希菌is an important cause of diarrhea in infants, especially in developing countries. EPEC adheres to the mucosal cells of the small bowel. Chromosomally mediated factors promote tight adherence. There is loss of microvilli (effacement), format

14、ion of filamentous actin pedestals or cup-like structures, and occasionally, entry of the EPEC into mucosal cells. The result of EPEC infection is watery diarrhea, which is usually self-limited but can be chronic.EPEC (Enteropathogenic E. coli )腸致病型大腸埃希菌Transmission electron micrograph Usually O157:

15、H7Pathogenic factors StxpiliDeath rate 35%Polluted food is an important infectious source. EHEC (Enterohemorrhagic E. coli )腸出血型大腸埃希菌The “l(fā)ife cycle” of E. coli O157:H75-10% prevalence in animals40% prevalence in farmsIntimate Adherence of EHEC to Epithelial CellsHemorrhagic bloody, copious diarrhea

16、few leukocytes afebrile hemolytic-uremic syndrome （HUS,溶血性尿毒綜合征）hemolytic anemiathrombocytopenia (low platelets)kidney failureEHEC (Enterohemorrhagic E. coli )腸出血型大腸埃希菌produces verotoxin, named for its cytotoxic effect on Vero cells, a line of African green monkey kidney cells. Verotoxin has many pr

17、operties that are similar to the Shiga toxin produced by some strains of Shigella dysenteriae type 1; however, the two toxins are antigenically and genetically distinct. EHEC has been associated with hemorrhagic colitis（出血性結(jié)腸炎）, a severe form of diarrhea, and with hemolytic uremic syndrome（溶血性尿毒綜合征）

18、, a disease resulting in acute renal failure, micro-angiopathic hemolytic anemia, and thrombocytopenia. Of the E. coli serotypes that produce verotoxin, O157:H7 is the most common and is the one that can be identified in clinical specimens.EHEC (Enterohemorrhagic E. coli )腸出血型大腸埃希菌Pathogenic factors

19、toxin，adhesinInfants chronic diarrhea(嬰兒持續(xù)性腹瀉)，dehydration(脫水)Bloody feces occasionallyEAggEC (Enteroaggregative E. coli )腸集聚型大腸埃希菌causes acute and chronic diarrhea (14 days in duration) in persons in developing countries. These organisms also are the cause of food-borne illnesses in industrialized

20、countries. The pathogenesis of EAEC-induced diarrhea is not well understood.EAggEC (Enteroaggregative E. coli )腸集聚型大腸埃希菌bacteriaPathogenic factorsdiseasesETECtoxin、colonization factorsinfants/travellers diarrheaEIECInvasive pro. (侵襲性外膜蛋白)resembles shigellosis（adults /children）EPECattachmentDiarrhea

21、in infantsEHEC“shiga-like” toxin、piliHemorrhagic colitis、HUSEAggECtoxin、adhesinChronic diarrhea in infantsPathogenic E.coli-brief summary(dysentery bacterium痢疾桿菌)No flagellum，motile(-)，H Ag(-)Ag and classificationO Ag： 4 groups A：痢疾志賀菌B：福氏志賀菌C：鮑氏志賀菌D：宋內(nèi)志賀菌一. Primary biological characteristicsresista

22、nceweak, heat labile, acid labile- send specimens immediatelymultiple drug-resistance(多重耐藥)一. Primary biological characteristicsPathogenic factorsInvasiveness(侵襲力)pili，invasive plasmid protein IpaD,B,C (coded by plasmid)toxinendotoxinexotoxin STShiga toxin（Stx） (coded by chromosome, also called vero

23、 toxin, VT)Three kinds of activities：enterotoxic, cytotoxic, neurotoxic二. pathogenicitylocal infection Dysentery bacterium attachment invasion of the mucosal epithelial cells the end of ileum（回腸） and colon（結(jié)腸） inflammation superficial ulceration, bleeding bloody feces二. pathogenicityDisease：Bacteria

24、l dysenteryblood and pus in stools infectious source：patients/carriers，faecal-oral route acute，chronic，poisoning二. pathogenicitydistributingnature, human being and animal intestine tractsG-, pili, flagellumAg structure and classificationO: group specific (42 groups), AE, IgMH: type specific , IgGVi:

25、 superficial Ag (microcapsule) 一. Primary biological characteristicsinvasiveness pili, Vi Agtoxin endotoxin enterotoxin (very few，similar to LT of ETEC)二. Pathogenic factors傷寒沙門菌 typhoid甲型副傷寒沙門菌 enteric fevers肖氏沙門菌(乙型副) paratyphoid希氏沙門菌 鼠傷寒沙門菌 gastroenteritis（food poisoning）腸炎沙門菌 septicemia豬霍亂沙門菌三.

26、Kinds and diseasesInfectious source：patients、carriersTransmitting route：gastro-intestinal tract四. Enteric fevers typhoid and paratyphoid bacteria phagocytosis腸系膜LD blood （bacteremia）1w (） 腸潰瘍 intestine 膽囊、肝、脾、腎等腸壞死 excreted in stools blood urine release腸出血、穿孔 （bacteremia）23w pathogenesis culture and

27、 identification feces、urine（23w） culture biochemical Ag-Ab reaction ( SS media) (雙糖鐵media)(agglutination on a slide) blood proliferate bacteria（bile broth）（1w）五. Diagnostic laboratory testsPrinciple: Tube dilution agglutination testresultOH: little probabilityOH: active infection is presentOH: early

28、 stage /other salmonellae infection (cross-reaction)OH: past immunization or past infectionNotice trends (注意動態(tài)觀察)(2) Widal test (肥達(dá)試驗)It is the tube dilution agglutination test and is used for the diagnosis of enteric fever. In general, serum agglutinin is sharply during the second and third weeks o

29、f salmonella infection. At least two serum specimens obtained at intervals of 710 days are needed to prove a rise in antibody titer. Serial (2 fold) dilutions of unknown serum are tested against antibodies from representation salmonella. The results are interpreted as follow: (1) High or rising titr

30、e O (1:160 or more) suggests active infection; (2) High titre H (1:160 or more) suggests past vaccination or past infection.This syndrome includes typhoid（傷寒） and paratyphoid（副傷寒）.Typhoid fever is a febrile illness produced by S. typhi. Paratyphoid fever is a mild form of this disease produced by S.

31、 paratyphi A, S. schottmuelleri（肖氏） and S. hirschfeldii（希氏）. The ingested salmonellae reach the small intestine from which they enter the lymphatics and then the blood-stream. They are carried by the blood to many organs including the liver, spleen, bone marrow and the intestine. The bacilli multipl

32、y in intestinal lymphoid tissue and are excreted in stools. After an incubation period of 1014 days, the fever rises to a high plateau and the spleen and liver become enlarged. Rose spots（玫瑰疹） can be seen on the skin of the abdomen or chest. The white blood cell count is normal or low. The chief com

33、plications are intestinal hemorrhage and perforation.Separate culture and identificationSeparate culture-selective medium /differential medium (鑒別)Pure culture、biochemical -glucose, lactose, H2S, motileSerologic methods-agglutination test on a slide to identify bacterial serogourps.Ag detectionimmun

34、oflurescence, SPA coagglutination- diagnose dysenteryAb detectionWidals test(肥達(dá)試驗) assistant diagnosis for Enteric FeversToxin detection-ELISA, RIA, gene probes腸道致病菌和非致病菌 (麥康凱 培養(yǎng)基,18hr,37)Reactions in TSI agar slants. Morphology, stainingG-, curved rods, single flagellum, active motileImportant path

35、ogensV. cholerae, V. parahemolyticus, others (e.g: 創(chuàng)傷弧菌)Sec.4 Vibrio (弧菌屬)I. Vibrio cholerae (霍亂弧菌) morphology and structuresG- , curved rod, a polar flagellum,actively motileDark-field or phase contrast microcopy may show the repidly motile vibrios (懸滴標(biāo)本可見“魚群樣穿梭”)Primary biological characteristics

36、culture alkaline media alkaline peptone water（pH8.59.5） alkaline agar plate Ag and classification O Ag-group specific,155 groups. O1, O139Primary biological characteristicsPathogenic factorsflagella, pili, toxin coregulated pilus A(毒素協(xié)調(diào)菌毛蛋白)cholera enterotoxin,CTdiseasecholeraAcute diarrhea, stools

37、like rice water, rapid loss of fluid and electrolytesCTBGM1adenyl cyclase (腺苷酸環(huán)化酶)ATPcAMPRapid secretionAA1A2V. Cholerae enterotoxin懸滴法Biological characteristicsgrows best in high concentrations of saltdiseaseFood poisoning (marine product/bloat product (鹽腌制品)二. V. parahaemolyticus 副溶血弧菌G-, curved o

38、r spiral shaped , S, or gull-wing shaped, multiple flagella at a polar and is actively motileUrease(+), oxindase and catalase (+)Chronic gastritis, ulcers, gastric carcinomaHelicobacter pylori, HP(幽門螺桿菌)G-, spiral shaped , S, or gull-wing shaped , polar flagella urea（C14-labeled urea）urease（脲酶） NH3+

39、 CO2* 10月3日，巴里馬歇爾（右）與羅賓沃倫得知自己獲得2005年諾貝爾生理學(xué)或醫(yī)學(xué)獎后，舉杯互相慶賀。 Campylobacter jejuni (空腸彎曲菌)distributing: animals, especially in the intestines of birds(禽類)and domestic animals (家畜)Biologic characteristicsG-, helix, S or sea-gull types, a single polar flagellumSec.6 Campylobacter (彎曲菌屬)Campylobacter jejuni (空腸彎曲菌)pathogenicityColonization (定植)，cytotoxin，heat labile enterotoxindiarrheaSec.6 Campylobacter (彎曲菌屬)G-,rods or vibrioscomplexed Ag-O,H, and superficial Ag K, ViPathogenic fact